Abstract: Bauxite residue recovery includes mixing a solution of hydrochloric acid (HCL) according to a predetermined concentration, and adding the HCL solution to a quantity of raw red mud recovered from industrial operations as waste material. The highly alkaline property of the bauxite residue, commonly known as red mud is at least partially neutralized from the HCL, and makes the resulting washed red mud more amenable to subsequent uses in various applications in fields such as construction, wastewater treatment, and metal recovery processes. The process recovers washed red mud from the red mud and HCL solution by filtering the raw red mud and HCL solution for generating a stream of leach liquor from the filtrate and the recovered washed red mud from the residue. The neutralized red mud is further treated to extract metals such as calcium, iron, aluminum, silicon, and titanium.

Abstract: Bauxite residue recovery includes mixing a solution of hydrochloric acid (HCL) according to a predetermined concentration, and adding the HCL solution to a quantity of raw red mud recovered from industrial operations as waste material. The highly alkaline property of the bauxite residue, commonly known as red mud is at least partially neutralized from the HCL, and makes the resulting washed red mud more amenable to subsequent uses in various applications in fields such as construction, wastewater treatment, and metal recovery processes. The process recovers washed red mud from the red mud and HCL solution by filtering the raw red mud and HCL solution for generating a stream of leach liquor from the filtrate and the recovered washed red mud from the residue.

Abstract: A low-temperature leaching operation employs a raw, red mud slurry directly from aluminum production for an oxalic acid leaching of ferric oxalate. Residual calcium, titanium, aluminum and other rare earths are also recoverable in a secondary stream. Monitoring and control of the pH of the leach solution yields soluble ferric oxalate without high temperatures or specific radiation or light sources. Addition of iron powder results in precipitation of ferrous oxalate, isolated by magnetic separation from the iron powder which recirculates in the solution. Magnetite may then be produced by heating the ferrous oxalate in low pO2 conditions.

Abstract: A vanadium recovery approach utilizes oil fly ash (OFA), in contrast to coal fly ash, for separation and recovery of vanadium. OFA is first carbon burned to reduce the volume for recycling, and also to provide a fuel for other industrial processes. Following an almost 90% weight reduction from carbon burning, the remaining material includes about 18% vanadium. A salt roasting performed at the same temperature (about 650° C.) as the carbon burning allows use of the same oven or furnace, reducing heat requirements for the overall process. Salt roasting generates a water-soluble material from which a water leaching process yields a vanadium leach solution containing recovered vanadium, avoiding a need for caustic or volatile leaching agents. Ammonium metavanadate is precipitated from the vanadium leach solution through addition of ammonium sulfate, and a calcination process used to generate vanadium oxide (V2O5).

Abstract: A low-temperature leaching operation employs a raw, red mud slurry directly from aluminum production for an oxalic acid leaching of ferric oxalate. Residual calcium, titanium, aluminum and other rare earths are also recoverable in a secondary stream. Monitoring and control of the pH of the leach solution yields soluble ferric oxalate without high temperatures or specific radiation or light sources. Addition of iron powder results in precipitation of ferrous oxalate, isolated by magnetic separation from the iron powder which recirculates in the solution. Magnetite may then be produced by heating the ferrous oxalate in low pO2 conditions.

Abstract: A vanadium recovery approach utilizes oil fly ash (OFA), in contrast to coal fly ash, for separation and recovery of vanadium. OFA is first carbon burned to reduce the volume for recycling, and also to provide a fuel for other industrial processes. Following an almost 90% weight reduction from carbon burning, the remaining material includes about 18% vanadium. A salt roasting performed at the same temperature (about 650° C.) as the carbon burning allows use of the same oven or furnace, reducing heat requirements for the overall process. Salt roasting generates a water-soluble material from which a water leaching process yields a vanadium leach solution containing recovered vanadium, avoiding a need for caustic or volatile leaching agents. Ammonium metavanadate is precipitated from the vanadium leach solution through addition of ammonium sulfate, and a calcination process used to generate vanadium oxide (V2O5).

Abstract: Methods of uniformly removing coatings from metallic substrates, such as tools and dies, without damaging the surface of the underlying substrate are provided. The processes are optimized for steel substrates with metallic carbide or nitride coatings. The methods encompass aqueous electrochemical removal using stirred, low temperature, basic electrolytes. Following removal of an old coating, a new coating may be applied, allowing recycle and reuse of the underlying metal substrate. The ability to recoat and reuse tools represents a significant cost savings.

Abstract: This application is dedicated to the public. A method and apparatus for reducing the emissions of a fluorinated gas from a wafer processing facility begins by providing a fluorinated exhaust gas from wafer processing tools (10) through (16) via an input line (17). The fluorinated exhaust gas is then optionally gettered via an gettering system (18) to remove oxygen from the exhaust gas. After gettering, the fluorinated exhaust gas is directed to a molten aluminum bath (44). The fluorine in the exhaust gas reacts with the aluminum to form AlF.sub.3. A measurement device (56) is used to monitor the amount of fluorine being exhausted from the molten aluminum bath (44). When the amount of fluorine in the exhaust is too high, the molten aluminum bath (44) is saturated with fluorine. The bath is then cooled to form an inert solid brick of AlF.sub.3. Therefore, fluorinated gases which are detrimental to the environment are cost-effectively removed from the output of a wafer fabrication facility.